1. Field
The present disclosure relates generally to register files, and more specifically, to methods and systems for providing energy efficient register files.
2. Background
An embedded processor design typically includes temporary storage such instruction caches, data caches and register files, etc. These storage components are relatively small, high speed memories that increase the speed of the processor by reducing the number of times the processor has to access slower external memory. Unfortunately, these storage components tend to consume a lot of power due to the switching capacitive loads. Larger components tend to switch more capacitive loads than smaller components, and therefore, consume more power. For example, after instruction and data caches, register files that are used as general purpose registers typically tend to consume more power than most of the other smaller components in an embedded processor design.
When an instruction is executed, appropriate source operands are first retrieved from the corresponding register file(s). After the instruction has been executed, results, if any, are written back into the register file(s). However, before these results are written back into the register file(s), one or more of these results are often needed for a subsequent instruction as a source operand and are thus taken by a forwarding network for further processing. The longer the pipeline the more likely that the source operands will be delivered to the forwarding network instead of the register file; furthermore, the more often the results are taken by the forwarding network, the longer the corresponding register file(s) have to wait before they are updated with the latest data. One ramification is that invalid data remain in the register file(s) for longer periods of time. If subsequent read operations are performed on register file(s) having invalid data, such read operations would produce incorrect results if used for instruction execution. In addition, power expended on such operations would be wasted. Hence, it would be desirable to provide an energy efficient means to prevent invalid read operations.